This invention relates to door seals of the type utilized adjacent to the opening of a building at a loading dock. Such structures provide a seal against the rear of a truck positioned at the loading dock in order to move goods from the truck into the building or from the building into the truck.
It is desirable, in certain instances, to provide a seal between the rear of a truck positioned at a building's loading dock and the building to prevent entry of warmer, outside air into refrigerated chambers within the truck and within the building while the truck is being loaded or unloaded or, under other circumstances, to prevent cold, outside air from entering the building while the loading dock door is open during loading or unloading of the truck. In other instances, however, it is highly undesirable for such a seal to be established between the truck and building. This occurs, for instance, during hot weather when the interior of a non-refrigerated truck will become unacceptably hot unless outside ventilation is provided.
Typical prior art sealing structures include those disclosed in the U.S. patents to Frommelt et al., U.S. Pat. Nos. 3,181,205, and 3,375,625, to Edkins et al., and German Pat. No. 2,930,295.
Laterally movable seals have been provided utilizing sliding door type tracks and hardware, but such tracks become filled with debris which make it difficult to move the seals, and the hardware binds so that the seals do not move freely.
Consequently, none of these prior art structures provide a convenient and practical means of selectively establishing or avoiding a seal between the rear of the truck and building, except by positioning the truck a distance away from the building, which typically is not acceptable because of the resulting gap between the rear of the truck bed and the floor of the loading dock or building.